It shall be unlawful for any person to run or otherwise move any tractor or similar engine across or over any culvert or bridge in any of the streets or alleys without first covering such bridge or culvert with good substantial plank of not less than four inches (4") in thickness so placed and arranged as to prevent the weight of such engine from resting on or being sustained by such bridge or culvert. (1996 Code § 6-1-1)